The present invention relates to a gear change device for shifting a transmission mounted on a vehicle.
A gear change device for shifting a transmission comprises a select actuator for actuating a shift lever of a speed-changing mechanism in a direction of selection and a shift actuator for actuating the shift lever in a direction of shift.
As the select actuator and shift actuator, there are usually used fluid pressure cylinders using a fluid pressure such as pneumatic pressure or hydraulic pressure as a source of operation. The select actuator and the shift actuator employing the hydraulic cylinders require pipes for connecting the source of fluid pressure to each of the actuators, require electromagnetic change-over valves for changing over the flow passage of the operation fluid, and require space for arranging the above components, resulting in an increase in weight of the apparatus as a whole.
In recent years, a select actuator and a shift actuator constituted by electric motors have been proposed as a gear change device for a transmission mounted on a vehicle which is provided with neither the source of compressed air nor the source of hydraulic pressure. The select actuator and the shift actuator constituted by electric motors can be constituted in a compact size as a whole and in a reduced weight since they need neither the pipes for connection to the source of hydraulic pressure nor the electromagnetic change-over valve unlike the actuators that use hydraulic cylinders.
The actuators using electric motors require a speed reduction mechanism for obtaining a predetermined operation force. As the speed reduction mechanisms, there have been proposed the one using a ball-screw mechanism and the one using a gear mechanism. However, the actuators using the ball-screw mechanism and the gear mechanism are not necessarily satisfactory in regard to durability of the ball-screw mechanism and of the gear mechanism and in regard to durability and the operation speed of the electric motors. Besides, the select actuator must reliably bring the shift lever to a predetermined select position.
It is, therefore, an object of the present invention to provide a gear change device equipped with a select actuator, which exhibits excellent durability, operates at a high speed, and can reliably bring a shift Lever to a predetermined select position.
In order to accomplish the above-mentioned object according to the present invention, there is provided a gear change device comprising a select actuator for actuating a shift lever in the direction of selection and a shift actuator for actuating the shift lever in the direction of shift; wherein
said select actuator comprises a cylindrical casing, a shift lever support mechanism arranged in said casing to support said shift lever in such a manner as to slide in the axial direction and to rotate, an electromagnetic solenoid for operating said shift lever in the axial direction which is the direction of selection, and a select position-limiting mechanism for limiting the operation position of the shift lever according to a thrust produced in response to the amount of electric power fed to the electromagnetic coils of said electromagnetic solenoids; and
said shift actuator rotates said shift lever support mechanism in the direction of shift.
The shift lever support mechanism comprises a control shaft mounting the shift lever and a rotary shaft which is spline-fitted to said control shaft in a manner to slide in the axial direction and is rotatably supported by said casing.
It is desired that the select actuator is so constituted that the shift lever is brought to a select position of the first speed gear in a state where no electric current has been fed to the electromagnetic coils of the electromagnetic solenoids.